Field
Aspects of the present invention generally relate to a technique for activating an information processing apparatus having a hibernation mechanism, at high speed.
Description of the Related Art
In recent years, increasing attention has been given to “hibernation” which can reduce power consumption of an information processing apparatus in a stand-by state. The hibernation is a system interruption mechanism. When a system is being activated, information in a memory, a central processing unit (CPU) register, or information about a device (hereinafter, referred to as “hibernation image”) is saved in a non-volatile storage device such as a hard disk. Even if the power is turned off subsequently, the system is restored to the same state as the previous state by reading the saved hibernation image when the system is activated next time (hereinafter, referred to as “hibernation activation”). The hibernation may be employed in order to shorten the activation time of the system.
Methods for activating the system through the hibernation can be roughly divided into two types. A method in which a restoration operation is executed by a basic input-output system (BIOS) function or a boot loader function, and a method in which a restoration operation is executed by a kernel function of an operating system are provided as the two types of activation methods.
In the hibernation activation by the kernel function, after initializing the kernel, a hibernation image previously stored in a non-volatile storage device is read to restore the state before the system was transferred to the hibernation. Compared to the hibernation activation by the BIOS, the hibernation activation by the kernel function is excellent in terms of general applicability because the device is initialized through a normal activation sequence.
Compared to the hibernation activation by the BIOS or the boot loader, the hibernation activation by the kernel function takes longer activation time because the activation sequence thereof requires longer processing time. Therefore, Japanese Patent Application Laid-Open No. 2001-022464 discloses a method in which the entire hibernation image is compressed and saved to a non-volatile storage device.